1. Field
The presently disclosed subject matter relates to a vehicle lamp, and more particularly to a vehicle signal lamp such as a tail lamp, a stop lamp and the like, which can provide a favorable light distribution pattern even when it is formed in a slender shape.
2. Description of the Related Art
A vehicle signal lamp such as a tail lamp, stop lamp, turning lamp, marking lamp. spot lamp, and the like is typically attached to a rear (but can be attached to a front or side) of a vehicle to inform other drivers about a driving state of the vehicle. Accordingly, the vehicle signal lamp has typically been formed to include a large light-emitting surface so that other drivers can easily confirm the driving signal. However, the rear of the vehicle may not be generally large because it is preferable to maintain a large rear window for safe driving. Therefore, the vehicle signal lamp tends to become a long and thin shape in a horizontal/vertical direction. In addition, it may be desirable to reduce a depth of the vehicle signal lamp so that the vehicle can maintain a large space for a trunk or for design criteria.
A conventional vehicle lamp such as a high mount stop lamp is disclosed in patent document No. 1 (Japanese Patent Application Laid Open H09-136571). FIGS. 13a and 13b are a horizontal and vertical cross-section view depicting a structure for the conventional high mount stop lamp. The conventional vehicle lamp of FIGS. 13a and 13b includes: a lamp body 60 including an opening; a lens 61 attached to the opening of the lamp body 60; and a bulb 62 located in the lamp body 60 and adjacent the lens 61.
The lamp body 60 includes: a rear surface portion 63 including a reflex surface 66 on an inner surface thereof; a top surface portion 64 connecting to the rear surface portion 63; and a bottom surface portion 65 connecting to the rear surface 65 so as to expand from the lens 61 toward the rear surface portion 66 in a vertical direction as shown in FIG. 13b. The reflex surface 66 is formed in a parabolic shape in a horizontal direction and is formed as a collecting surface having a shape such as a circular shape, an ellipsoidal shape and the like in the vertical direction.
The bulb 62 is attached to the bottom surface portion 65 of the lamp body 60 so that a filament of the bulb 62 is located at a focus of the reflex surface 66, which is located on an optical axis X of the parabolic shape in the horizontal direction and is located at a first focus of the ellipsoidal surface in the vertical direction. The lens 61 includes an inner surface 67 and an outer surface 68, and forms a fisheye lens with the inner and outer surfaces.
In the structure of the conventional vehicle lamp, a direct light L1 emitted from the bulb 62 may enter into the lens 61. A reflected light L2 that is emitted from the bulb 62 and is reflected on the reflex surface 66 may pass in a direction parallel with the optical axis X in the horizontal direction and may pass so as to converge in the vertical direction, and the reflected light L2 may enter into the lens 61.
The lights L1 and L2 are emitted in a direction toward a light-emission of the vehicle lamp via the lens 61 while they are focused by the lens 61. Therefore, the conventional vehicle lamp can emit the light L1 and L2 with a wide range using the lens 61 and the reflex surface 66, which are formed in a wide and thin shape.
The above-referenced Patent Document is listed below and is hereby incorporated with its English abstract in its entirety.    1. Patent document No. 1: Japanese Patent Application Laid Open H09-136571
However, in the above-described structure of the conventional vehicle lamp, though the bulb 62 is located at the first focus of the ellipsoidal surface in the vertical direction, a second focus of the ellipsoidal surface may not be determined. Accordingly, a focus point of the reflected light L2 may not be determined, and a direction of each the light rays that pass through the lens 61 may not be determined. Therefore, because it is difficult for the conventional structure to control a light distribution, it may be difficult for the conventional vehicle lamp to realize a desired light distribution pattern.
In addition, because the bulb 62 is attached to the bottom surface portion 65 of the lamp body 63, a height of the rear surface portion 63 may become high as compared with that of the lens 61. Thus, an attachment structure of the conventional vehicle lamp may become complex, and a light use efficiency of the vehicle lamp may not be high.
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include a vehicle lamp having a favorable light distribution even when a lens and a reflector are formed in a long and thin shape. In this case, various light sources such as a semiconductor light source, an HID lamp, a halogen bulb and the like can be employed as a light source with a simple structure and substantially the same structure.